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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Try replacing your ST_Collect call with ST_Union.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>ST_Collect when used with polygons will create invalid multipolygons since it just collects them up, and if they are adjacent, it's not a valid multipolygon.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Hope that helps,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Regina<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><a href="http://www.postgis.us">http://www.postgis.us</a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><a href="http://postgis.net">http://postgis.net</a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal style='margin-left:.5in'><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> postgis-users [mailto:postgis-users-bounces@lists.osgeo.org] <b>On Behalf Of </b>Michael Treglia<br><b>Sent:</b> Thursday, May 26, 2016 10:34 PM<br><b>To:</b> PostGIS Users Discussion <postgis-users@lists.osgeo.org><br><b>Subject:</b> [postgis-users] Topology Issue Reported by Query but Not Identified with ST_IsValid<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p><div><p class=MsoNormal style='margin-left:.5in'>Hi All,<o:p></o:p></p><div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>I was running a query involving ST_Difference between two multipolygon layers, and a while in, it threw this message: <o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>ERROR: GEOSDifference: TopologyException: side location conflict at 919670.1768945494 140665.82566365649<o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>However, I previously ran ST_MakeValid, and ST_IsValid doesn't report any objects with problems. Is there something I'm missing, or something else I need to check? (Apologies is this is just a naive question - still learning my way around PostGIS).<o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>And in case it helps, here's my SQL:<o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'> <o:p></o:p></p></div><div><div><p class=MsoNormal style='margin-left:.5in'>CREATE TABLE SI_Unclaimed AS<o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>SELECT gid, COALESCE(ST_Difference(geom_2263, (SELECT ST_Collect(b.geom_2263) <o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'> FROM citywide_basedata.parcels15 b<o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'> WHERE ST_Intersects(a.geom_2263, b.geom_2263)<o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'> )), a.geom_2263)<o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>FROM citywide_basedata.boroughs_nowater a where boroname like 'Staten Island';<o:p></o:p></p></div></div><div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>Thanks!<o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>Mike<o:p></o:p></p></div></div></div></body></html>